Systems and methods for testing neural stimulation sites

ABSTRACT

Various system embodiments comprise a medical device, comprising a flexible tether, a neural stimulation circuit, and a controller. The flexible tether is adapted to be fed into a patient&#39;s throat. The flexible tether includes a plurality of electrodes. The neural stimulation circuit is adapted to deliver neural stimulation. The controller is adapted to control the neural stimulation circuit to provide a neural stimulation therapy using at least one electrode from the plurality of electrodes, and to implement a neural stimulation test routine. The neural stimulation test routine is adapted to assess neural stimulation efficacy for electrode subsets of the plurality of electrodes to identify a desired electrode subset for use in delivering the neural stimulation therapy to elicit a desired response.

CLAIM OF PRIORITY

This application is a continuation of and claims the benefit of priorityunder 35 U.S.C. §120 to Libbus et al., U.S. patent application Ser. No.11/624,300, filed on Jan. 18, 2007, now issued as U.S. Pat. No.8,301,239, which is hereby incorporated by reference herein in itsentirety.

FIELD

This application relates generally to medical devices and, moreparticularly, to systems, devices and methods for providing acuteautonomic stimulation.

BACKGROUND

A reduced autonomic balance during heart failure has been shown to beassociated with left ventricular dysfunction and increased mortality.This reduced autonomic balance increases sympathetic and decreasesparasympathetic cardiac tone. Direct stimulation of the vagalparasympathetic fibers has been shown to reduce heart rate viaactivation of the parasympathetic nervous system and indirect inhibitionof the sympathetic nervous system. Some data indicate that increasingparasympathetic tone and reducing sympathetic tone may protect themyocardium from further remodeling and predisposition to fatalarrhythmias following myocardial infarction; and some data indicatesthat chronic stimulation of the vagus nerve may protect the myocardiumfollowing cardiac ischemic insult. However, implantation of electrodesis an invasive procedure, and it can be difficult to immediately implantelectrodes after a myocardial infarction.

SUMMARY

Various system embodiments comprise a medical device, comprising aflexible tether, a neural stimulation circuit, and a controller. Theflexible tether is adapted to be fed into a patient's throat. Theflexible tether includes a plurality of electrodes. The neuralstimulation circuit is adapted to deliver neural stimulation. Thecontroller is adapted to control the neural stimulation circuit toprovide a neural stimulation therapy using at least one electrode fromthe plurality of electrodes, and to implement a neural stimulation testroutine. The neural stimulation test routine is adapted to assess neuralstimulation efficacy for electrode subsets of the plurality ofelectrodes to identify a desired electrode subset for use in deliveringthe neural stimulation therapy to elicit a desired response.

Various system embodiments comprises means for automatically selectingat least one electrode from a plurality of electrodes located in apharynx, a larynx, a trachea, or an esophagus of a patient. The meansfor selecting at least one electrode includes means for determining thatthe selected at least one electrode is effective for use in deliveringneural stimulation to elicit a desired response. Various systemembodiments further comprise means for automatically delivering a neuralstimulation therapy using the selected at least one electrode.

According to various method embodiments, an emergency patient isidentified as a candidate for post myocardial infarction (post-MI)neural stimulation therapy. A flexible tether of a portable device isinserted into the patient's throat. The flexible tether includes aplurality of electrodes. Autonomic neural stimulation is delivered to adesired neural target to elicit a desired neural response for thepost-MI neural stimulation therapy.

A portable medical device embodiment comprises a flexible tether, aneural stimulation circuit, a battery terminal adapted to receive atleast one battery, and a controller. The flexible tether is adapted tobe fed into a patient's throat, and includes at least one neuralstimulation element for use in delivering neural stimulation to a neuraltarget. The neural stimulation circuit is adapted to deliver neuralstimulation using the at least one neural stimulation element. Thebattery terminal is connected to the neural stimulation circuit and thecontroller to enable the at least one battery to power the neuralstimulation circuit and the controller. The controller is adapted tocontrol the neural stimulation circuit to provide an autonomic neuralstimulation therapy using the at least one neural stimulation element.According to various embodiments, the neural stimulation element may bean electrode, a transducer adapted to deliver ultrasound energy, atransducer adapted to deliver light energy, a transducer adapted todeliver magnetic energy, or a transducer adapted to deliver thermalenergy.

This Summary is an overview of some of the teachings of the presentapplication and not intended to be an exclusive or exhaustive treatmentof the present subject matter. Further details about the present subjectmatter are found in the detailed description and appended claims. Otheraspects will be apparent to persons skilled in the art upon reading andunderstanding the following detailed description and viewing thedrawings that form a part thereof, each of which are not to be taken ina limiting sense. The scope of the present invention is defined by theappended claims and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the physiology of the upper respiratory/digestivesystems.

FIG. 2 illustrates the vagus nerve superimposed on the upperrespiratory/digestive systems illustrated in FIG. 1.

FIG. 3 illustrates an embodiment where a flexible tether is fed througha mouth into a patient's throat to position electrode(s) in the pharynx.

FIG. 4 illustrates an embodiment where a flexible tether is fed througha mouth into a patient's throat to position electrode(s) in theesophagus, and to also position electrodes in the pharynx.

FIG. 5 illustrates an embodiment where a flexible tether is fed througha mouth into a patient's throat to position electrode(s) in the trachea,and to also position electrodes in the pharynx and/or larynx.

FIG. 6 illustrates an embodiment where a flexible tether is fed througha nose into a patient's throat to position electrode(s) in the pharynx.

FIG. 7 illustrates an embodiment of a portable neural stimulator with atleast one electrode in the respiratory or digestive pathway and acounter electrode on a patient's skin.

FIG. 8 illustrates various embodiments of a portable neural stimulatorto stimulate the vagus nerve.

FIG. 9 illustrates an embodiment of a tether with annular stimulationelectrodes, according to various embodiments.

FIGS. 10A and 10B illustrate an embodiment of a tether with stimulationelectrodes, where the illustrated electrodes do not circumscribe thetether.

FIG. 11 illustrates a transluminal neural stimulation using electrodeswithin the lumen, according to various embodiments.

FIG. 12 illustrates neural stimulation using an external counterelectrode, according to various embodiments.

FIGS. 13A through 13E are illustrations of electrode configurations usedby the present system, according to various embodiments.

FIG. 14 illustrates a method for using the portable neural stimulator,according to various embodiments.

FIG. 15 illustrates a method for automatically performing a neuralstimulation test routine, according to various embodiments.

FIG. 16 illustrates a method for automatically performing the neuralstimulation test routine, according to various embodiments.

DETAILED DESCRIPTION

The following detailed description of the present subject matter refersto the accompanying drawings which show, by way of illustration,specific aspects and embodiments in which the present subject matter maybe practiced. These embodiments are described in sufficient detail toenable those skilled in the art to practice the present subject matter.Other embodiments may be utilized and structural, logical, andelectrical changes may be made without departing from the scope of thepresent subject matter. References to “an”, “one”, or “various”embodiments in this disclosure are not necessarily to the sameembodiment, and such references contemplate more than one embodiment.The following detailed description is, therefore, not to be taken in alimiting sense, and the scope is defined only by the appended claims,along with the full scope of legal equivalents to which such claims areentitled.

The present subject matter provides a portable, external device with aflexible tether adapted to pass electrode(s) through a patient's nose ormouth into, and in some embodiments through, the patients throat.Various embodiments pass the stimulation electrode(s) through thepatient's throat into the patient's trachea, using orotrachealintubation (passing the endotracheal tube through the mouth, through thelarynx, and into the trachea) or using nasotracheal intubation (passingthe tube through the nose, through the larynx, and into the trachea).Various embodiments pass the stimulation electrode(s) through thepatient's throat into the patient's larynx. Various embodiments pass thestimulation electrode(s) through the patient's throat into the patient'sesophagus. The electrode(s) are positioned to provide stimulation of thevagus nerve.

In various embodiments, the flexible tether includes a flexibleintubation tube to be placed in the patient's throat. The flexibleintubation tube can be similar to tubes used in a transesophagealechocardiogram (TEE) system. The tube is designed to be inserted intothe patient's throat, either passively (if the patient is conscious) oractively. For example, if the patient is conscious, the patient canswallow the tube to advance the tube into the throat, and to furtheradvance the tube into the esophagus. If the patient is not conscious,the tube can be inserted through the nose or mouth into the throat. Theend of the tube can be positioned in the pharynx, the larynx, thetrachea or the esophagus. Sedatives can be administered to reducediscomfort and increase relaxation. A mouthpiece can be used to guidethe tube into the throat. The tube itself can be lubricated to assistwith the insertion procedure.

In various embodiments, the device is adapted to provide airwaymanagement. The tube includes an open lumen which is used in conjunctionwith an external air bladder for mechanical ventilation. For embodimentsthat provide airway management, the tube is inserted along the airwaypathway (e.g. the end of the tube is positioned along the pathway thatincludes the pharynx, larynx, and trachea).

Various embodiments provide a plurality of stimulation electrodes on theexternal surface of the tube. These electrodes can be used to provideemergency parasympathetic stimulation by transesophageal activation ofthe vagus nerve (or branches thereof). In various embodiments, the tubecontains one or more electrodes which is used to provide unipolarstimulation in conjunction with an external electrode, placed on thepatient's skin. Various embodiments also use the counter electrode forother purposes (e.g. skin electrode for electrocardiogram recording, orfor external pacing or defibrillation). Stimulation can occur from anintraesophageal electrode(s) with counter electrode(s) placed anywhereelse on or in the body.

The portable external device can be used by a first responder, who mayprovide on-the-scene emergency parasympathetic stimulation. For example,this device may be used to provide parasympathetic therapy in theminutes or hours following an acute myocardial infarction (MI).Immediate therapy is known to be of critical importance in preventingcardiac damage following an acute MI.

Physiology of the Upper Respiratory/Digestive System and the Vagus Nerve

FIG. 1 illustrates the physiology of the upper respiratory/digestivesystems. The figure illustrates a nasal cavity 101, and a mouth cavity102 separating a soft palate 103 and tongue 104. The figure alsoillustrates a throat, generally identified as including a pharynx 105and fauces 106. The term fauces refers to the space between the cavityof the mouth and the pharynx, bounded by the soft palate and the base ofthe tongue. The pharynx is part of the digestive system and respiratorysystem, and is situated posterior to the mouth and nasal cavity, andcranial to the esophagus 107, larynx 108 and trachea 109. The humanpharynx can be divided into the nasopharynx (the region lying behind thenasal cavity), the oropharynx (the region lying behind the mouthcavity), and the hypopharynx, also knows as the laryngopharynx. Thehypopharynx lies directly posterior to the upright epiglottis 110 andextends to the larynx, where the respiratory and digestive pathwaysdiverge. The digestive pathway proceeds to the esophagus, and therespiratory pathway proceeds to the larynx and the trachea. Theesophagus 107 conducts food and fluids to the stomach. Air enters thelarynx anteriorly. The epiglottis 110 is a thin, lid-like flap ofcartilage tissue attached to the root of the tongue that is normallypointed upward, but temporarily folds down over the entrance to thevocal cords to stop the air passage when swallowing solids or liquids toprevent food and water from passing into the trachea. The larynx 108 isan organ of voice production, as it houses the vocal cords, and issituated in the part of the respiratory tract just below where the tractof the pharynx splits into the trachea and the esophagus. The trachea109, or windpipe, is the air tube extending from the larynx into thethorax.

FIG. 2 illustrates a vagus nerve 211 superimposed on the upperrespiratory/digestive systems illustrated in FIG. 1. The vagus nerve 211has a more extensive course and distribution than any of the othercranial nerves, since it passes through the neck and thorax to theabdomen. The vagus nerve supplies nerve fibers to the pharynx 205(throat), larynx 208 (voice box), trachea 209 (windpipe), lungs, heart,esophagus 207, and the intestinal tract as far as the transverse portionof the colon. The vagus nerve also brings sensory information back tothe brain from the ear, tongue, pharynx, and larynx.

As identified by Henry Gray's Anatomy of the Human Body, thedistribution of the vagus nerve is complex. The vagus nerve passesvertically down the neck within the carotid sheath, lying between theinternal jugular vein and internal carotid artery as far as the upperborder of the thyroid cartilage, and then between the same vein and thecommon carotid artery to the root of the neck. The further course of thenerve differs on the two sides of the body. On the right side, the nervepasses across the subclavian artery between it and the right innominatevein, and descends by the side of the trachea to the back of the root ofthe lung, where it spreads out in the posterior pulmonary plexus. Fromthe lower part of this plexus two cords descend on the esophagus, anddivide to form, with branches from the opposite nerve, the esophagealplexus. Below, these branches are collected into a single cord, whichruns along the back of the esophagus enters the abdomen, and isdistributed to the postero-inferior surface of the stomach, joining theleft side of the celiac plexus, and sending filaments to the lienalplexus. On the left side, the vagus enters the thorax between the leftcarotid and subclavian arteries, behind the left innominate vein. Itcrosses the left side of the arch of the aorta, and descends behind theroot of the left lung, forming there the posterior pulmonary plexus.From this it runs along the anterior surface of the esophagus, where itunites with the nerve of the right side in the esophageal plexus, and iscontinued to the stomach, distributing branches over its anterosuperiorsurface; some of these extend over the fundus, and others along thelesser curvature. Filaments from these branches enter the lesseromentum, and join the hepatic plexus.

The branches of distribution of the vagus nerve in the neck include thepharyngeal, superior laryngeal, recurrent and superior cardiac branches.The branches of distribution of the vagus nerve in the thorax includethe inferior cardiac, anterior bronchial, posterior bronchial, andesophageal branches. The pharyngeal branch is the principal motor nerveof the pharynx. The superior laryngeal nerve descends by the side of thepharynx, behind the internal carotid artery, and divides into externaland internal branches. The external branch of the superior laryngealnerve descends on the larynx, branches to the pharyngeal plexus andcommunicates with the superior cardiac nerve. The internal branch of thesuperior laryngeal nerve is distributed to the mucous membrane of thelarynx, where some branches are distributed to the epiglottis and otherpass backward to supply the mucous membrane surrounding the entrance ofthe larynx. The right side of the recurrent branch ascends obliquely tothe side of the trachea behind the common carotid artery, and the leftside of the recurrent branch ascends to the side of the trachea. Oneither side, the recurrent nerve ascends in the groove between thetrachea and esophagus, and enters the larynx. As the recurrent nerveascend in the neck, it branches to the mucous membrane and muscular coatof the esophagus, the mucous membrane and muscular fibers of thetrachea, and some pharyngeal filaments branch to the constrictorpharyngis inferior. The esophageal branches form the esophageal plexus.

This brief discussion illustrates that there are a number of vagus nervesites along the digestive and respiratory pathways. The present subjectmatter provides stimulation electrode(s) within the digestive pathway,the respiratory pathway or both the digestive and respiratory pathwaysfor use in delivering neural stimulation that targets at least some ofthese vagus nerve sites.

Embodiments for Positioning Flexible Tether

FIG. 3 illustrates an embodiment where a flexible tether 312 is fedthrough a mouth into a patient's throat to position electrode(s) in thepharynx 305. The illustrated flexible tether includes one electroderegion 313 at or near the distal portion of the lead. The electroderegion includes a number of potential electrodes capable of beingselected for use to deliver the neural stimulation.

FIG. 4 illustrates an embodiment where a flexible tether 412 is fedthrough a mouth into a patient's throat to position electrode(s) in theesophagus 407, and to also position electrodes in the pharynx 405. Theillustrated flexible tether includes a first electrode region 413 at ornear the distal portion of the lead, which is illustrated as beingpositioned in the esophagus. Also, as illustrated, various embodimentsof the flexible tether provide a second electrode region 414,illustrated as being positioned in the pharynx. Each of the electroderegions includes a number of potential electrodes capable of beingselected for use to deliver the neural stimulation. Some embodimentsprovide a larger electrode region that encompasses the illustrated firstand second electrode regions. Some tether embodiments provide additionalelectrode regions.

FIG. 5 illustrates an embodiment where a flexible tether 512 is fedthrough a mouth into a patient's throat to position electrode(s) in thetrachea 509, and to also position electrodes in the pharynx 505 and/orlarynx 508. The illustrated flexible tether includes a first electroderegion 513 at or near the distal portion of the lead, which isillustrated as being positioned in the trachea. Also, as illustrated,various embodiments of the flexible tether provide a second electroderegion 514, illustrated as being positioned in the pharynx and/orlarynx. Each of the electrode regions includes a number of potentialelectrodes capable if being selected for use to deliver the neuralstimulation. Some embodiments provide a larger electrode region thatencompasses the illustrated first and second electrode regions. Sometether embodiments provide additional electrode regions.

FIG. 6 illustrates an embodiment where a flexible tether 612 is fedthrough a nose into a patient's throat to position electrode(s) in thepharynx 605. The illustrated flexible tether includes one electroderegion 613 at or near the distal portion of the lead. The electroderegion includes a number of potential electrodes capable of beingselected for use to deliver the neural stimulation. The tether fedthrough the nose cavity can further be fed into the esophagus or thetrachea, similar to the tethers illustrated in FIGS. 4 and 5. More thanone electrode region can also be implemented on the flexible tether.

Various embodiments deliver electrode regions in various combinations ofthe pharynx, the larynx, the trachea and the esophagus using one or moretethers. The electrode regions positioned in these areas can be used tocreate stimulation vectors between two or more of the pharynx, thelarynx, the trachea and the esophagus.

System Embodiments

FIG. 7 illustrates an embodiment of a portable neural stimulator with atleast one electrode in the respiratory or digestive pathway and acounter electrode on a patient's skin. The illustrated position of thecounter electrode is provided as an example. Those of ordinary skill inthe art will understand, upon reading and comprehending this disclosure,that the counter electrode can be placed elsewhere on the patient'sskin, such as locations on the neck, chest, back and the like. Thefigure illustrates a portable device 715 that includes the portableneural stimulator 716 and a mechanical ventilator 717, both powered by abattery source 718. Some embodiments provide the mechanical ventilatorand the neural stimulator as separate devices with separate powersources. Various embodiments do not include a mechanical ventilator.

A flexible tether 712 is illustrated as being fed through the mouth toplace an electrode region 713 in the pharynx of the patient. Theflexible tether 712 includes electrical conductor(s) 719 connected tothe electrode(s) in the electrode region, and further includes a tube720 adapted to deliver gas to the patient. Various embodiments providethe conductor(s) 719 and tube 720 in a separate sheathing. Variousembodiments route the conductor(s) 719 within the tube 720. Variousembodiments route the conductor(s) 719 on the external wall of the tube720. In various embodiments, the flexible tube 720 is formed withconductive traces that are used to provide the conductor(s) to theelectrode region. The conductor(s) are electrically insulated to preventunwanted shocks to the tongue, mouth, and the like. The illustratedneural stimulator 716 is also connected to a counter electrode 721positioned on the patient's skin. Various embodiments use a patch withan adhesive for securing the patch and the counter electrode(s) to thepatient's skin. Electrical vectors can be provided between or amongelectrodes on the flexible tether and counter electrode(s) on thepatient's skin. More than one counter electrode per patch, and more thanone patch can be used (for example, a patch on the neck, a patch on theback, a patch on the chest, or various combinations thereof). Given theposition and number of stimulation electrodes, some device embodimentsare capable of delivering unipolar stimulation, bipolar stimulation,multipolar stimulation, or various combinations thereof to provide anumber of stimulation vectors. Various counter electrode embodimentsinclude surface electrodes placed on the surface of the skin, andvarious counter electrode embodiments include percutaneous electrodes.Various embodiments use the counter electrode(s) to sense heart rate orblood pressure.

FIG. 8 illustrates various embodiments of a portable neural stimulatorto stimulate the vagus nerve. The illustrated neural stimulatorembodiment 816 includes a neural stimulation circuit 822, a feedbackcircuit 823, a controller 824, and memory 825. The illustratedembodiment further includes at least one port 826 to connect to at leastone lead 827. The flexible tether illustrated in previous figures canfunction as a lead. A lead can also be used to connect the counterelectrode to the neural stimulator. The neural stimulation circuit isconnected to the port(s) to provide a neural stimulation signal to atleast one neural stimulation electrode 828 on the lead(s) to elicit avagus nerve response when an appropriate signal is provided to anappropriately-positioned neural stimulation electrode. The feedbackcircuit 823 is connected to the port(s) to receive a signal from thephysiology sensor 829. The sensor senses a physiology function thatdepends, at least in part, on vagal stimulation. Examples of suchfunctions includes heart rate, blood pressure, ECG waveforms, andrespiration. Thus, various embodiments implement a heart rate sensor asthe physiology sensor, and various embodiments implement a bloodpressure sensor as the physiology sensor. Various embodiments provide asensor capable of directly detecting the heart rate from the carotidartery, and various embodiments provide a sensor capable of directlydetecting blood pressure from the carotid artery. One example of such asensor is an acoustic sensor adapted to sense blood flow. The sensedblood flow is capable of being used to determine blood pressure and/orheart rate. However, other sensor technology can be used.

The memory 825 includes computer-readable instructions that are capableof being operated on by the controller to perform functions of thedevice. Thus, in various embodiments, the controller is adapted tooperate on the instructions to provide programmed neural stimulationtherapies 830 such as post-MI according to a neural stimulation therapyschedule stored in the memory. Various “closed loop” systems vary theintensity of the neural stimulation, as generally illustrated by thestimulation intensity module 831, based on the sensed physiology signalreceived by the feedback circuit according to a preprogrammed therapy toprovide a desired affect. Thus, the closed loop system is capable ofreducing and increasing the neural stimulation intensity as appropriateto maintaining some measured physiological parameters within an upperand lower boundary during the vagal stimulation therapy. Various “openloop” systems without feedback from the physiology signal also can beprogrammed to vary the stimulation intensity. Various embodimentsmodulate the stimulation intensity by modulating the amplitude of theneural stimulation signal, the frequency of the neural stimulationsignal, the duty cycle of the neural stimulation signal, the duration ofa stimulation signal, the waveform of the neural stimulation signal, thepolarity of the neural stimulation signal, or any combination thereof.

Various embodiments automatically change the electrode configuration, asgenerally illustrated by the electrode configuration module 832 of thecontroller 824. The illustrated electrode configuration module 832 isadapted to control switches 833 to control which electrodes of theavailable electrodes are used to deliver the neural stimulation, and thestimulation vectors for the electrodes. Additionally, the illustratedelectrode configuration module 832 is adapted to work with thestimulation intensity module 831 to control the stimulation intensityfor the different electrode combinations and stimulation vectors. Thus,for example, the electrode configuration module 832 can find a referenceneural stimulation level for a particular electrode combination andvector, and the stimulation intensity module 831 can further modulatethe neural stimulation based on the reference neural stimulation level.A neural stimulation test routine stored in the memory 825 controls theprocess of testing for an efficacious electrode configuration from theavailable electrode configurations.

The illustrated device is a portable device, that is illustrated asbeing powered by a battery 834, which can be easily removed and replacedfrom a battery terminal of the device. The portable device also includesan actuator 835. In various embodiments, the actuator is used toinitiate the neural stimulation test routine, and automatically deliverthe neural stimulation therapy upon completion of the neural stimulationtest routine. Thus, for example, an emergency responder can feed theflexible tube into a patient's throat, and then actuate the device toinitiate the neural stimulation test routine, and automatically deliverthe neural stimulation therapy upon completion of the neural stimulationtest routine. The actuator can be a mechanical switch on the housing ofthe portable device. The mechanical switch can also power up the device,and initiate the test routine after power up. Various embodiments use adisplay and user interface(s), such as a touch screen, as an actuator toinitiate the test routine. Various embodiments use an interface with onebutton or switch used to initiate the test routine for selecting theelectrode configuration, and another button or switch to turn thestimulation therapy on or off. Various interface embodiments respond tovoice commands. A simple, automated interface can step a user throughthe process, allowing the user to accurately deliver the therapy withoutsignificant, special training to operate the device. In variousembodiments, the controller automatically implements the neuralstimulation test routine. In various embodiments, the controller anduser interface cooperate to implement a neural stimulation test routineto allow a user to select the at least one of the neural stimulationelectrodes to use in delivering the autonomic neural stimulationtherapy. For example, the user interface can display test results forvarious electrode configurations. The information identifying theelectrode configurations can include the electrodes used in thestimulation, the stimulation amplitude, the stimulation frequency, thestimulation duty cycle, the stimulation duration, the stimulationwaveform, and the stimulation polarity. The test results can include thedetected physiologic response (e.g. heart rate) attributed to the neuralstimulation for an electrode configuration. The user can review the testresults, and select an electrode configuration using the test results.

Electrode Configurations

The neural stimulation test routine is adapted to assess neuralstimulation efficacy for electrode subsets of a plurality of electrodesto identify a desired electrode subset for use in delivering the neuralstimulation therapy to elicit a desired response. Each electrode subsetof the plurality of electrodes includes at least one electrode. Theelectrode subsets can include various combinations of electrodesselected from the plurality of electrodes, including all of theelectrodes in the plurality of electrodes.

A number of electrode configurations can be used. The illustrationsincluded herein are provided as examples, and are not intended to be anexhaustive listing of possible configurations.

FIG. 9 illustrates an embodiment of a tether 912 with annularstimulation electrodes 936 that form an electrode region 913, accordingto various embodiments. Any one or combination of the annularstimulation electrodes can be used to deliver the neural stimulation.

FIGS. 10A and 10B illustrate an embodiment of a tether 1012 withstimulation electrodes 1037, where the illustrated electrodes do notcircumscribe the tether. Thus, a subset of the illustrated electrodescan be selected to provide directional stimulation. For example, thetether may twist or rotate as it is fed into a patient's throat, and itmay be desired to stimulate a neural target on one side of the tetherwithout stimulating other nerves or tissue on the other sides of thetether. A neural stimulation test routine can cycle through theavailable electrodes for use in delivering the neural stimulation todetermine which subset of electrodes are facing toward the neuraltarget.

FIG. 11 illustrates a transluminal neural stimulation using electrodeswithin the lumen, according to various embodiments. The figureillustrates a lumen 1138 (e.g. trachea, esophagus, pharynx, larynx), anerve 1139 external to the lumen, and a flexible tether 1112 within thelumen. The neural stimulation generates an electrical field 1140 betweenthe electrodes that extends past the lumen wall to the nerve. As thevagus innervates the pharynx, larynx, trachea and esophagus, nerveendings may be stimulated in the lumen wall as well.

FIG. 12 illustrates neural stimulation using an external counterelectrode, according to various embodiments. The figure illustrates alumen 1238 (e.g. trachea, esophagus, pharynx, larynx), a nerve 1239external to the lumen, a flexible tether 1212 within the vessel, and acounter electrode 1221 on the patient's skin (e.g. neck). The neuralstimulation generates an electrical vectors 1241 between the electrodesthat extends past the vessel wall to the nerve.

FIGS. 13A through 13E are illustrations of electrode configurations usedby the present system, according to various embodiments. In theembodiment illustrated in FIG. 13A, a first electrode configuration 1351is used to deliver neural stimulation by generating an electrical signalfrom electrode A to electrode B. In this embodiment, if an efficacy ofthe first electrode configuration is lower than a threshold, the systemswitches to a second electrode configuration 1352 to deliver neuralstimulation by generating an electrical signal from electrode C toelectrode D. Electrodes A, B, C and D may be part of the same electroderegion or may be different electrode regions, in various embodiments.

In the embodiment illustrated in FIG. 13B, a first electrodeconfiguration 1353 is used to deliver neural stimulation by generatingan electrical signal from electrode E to electrode F and from electrodeG to electrode F. In this embodiment, if an efficacy of the firstelectrode configuration is lower than a threshold, the system switchesto a second electrode configuration 1354 by removing an electrode (hereelectrode G) to deliver neural stimulation by generating an electricalsignal from electrode E to electrode F. Electrodes E, F and G may bepart of the same electrode region or may be different electrode regions,in various embodiments.

In the embodiment illustrated in FIG. 13C, a first electrodeconfiguration 1355 is used to deliver neural stimulation by generatingan electrical signal from electrode H to electrode I. In thisembodiment, if an efficacy of the first electrode configuration is lowerthan a threshold, the system switches to a second electrodeconfiguration 1356 by adding an electrode (here electrode J) to deliverneural stimulation by generating an electrical signal from electrode Hto electrode I and from electrode J to electrode I. Electrodes H, I andJ may be part of the same electrode region or may be different electroderegions, in various embodiments.

In the embodiment illustrated in FIG. 13D, a first electrodeconfiguration 1357 is used to deliver neural stimulation by generatingan electrical signal from electrode K to electrode L. In thisembodiment, if an efficacy of the first electrode configuration is lowerthan a threshold, the system switches to a second electrodeconfiguration 1358 by generating an electrical signal from electrode Kto electrode M. Electrodes K, L and M may be part of the same electroderegion or may be different electrode regions, in various embodiments.

In the embodiment illustrated in FIG. 13E, a first electrodeconfiguration 1359 is used to deliver neural stimulation by generatingan electrical signal from electrode N to electrode P. In thisembodiment, if an efficacy of the first electrode configuration is lowerthan a threshold, the system switches to a second electrodeconfiguration 1360 by generating an electrical signal from electrode Oto electrode P. Electrodes N, O and P may be part of the same electroderegion or may be different electrode regions, in various embodiments.Other embodiments of electrode configurations that are adapted tostimulate a neural target are within the scope of this disclosure. Invarious embodiments, switching electrode configuration changesstimulation from bipolar to unipolar. In various embodiments, switchingelectrode configuration changes stimulation among a unipolarstimulation, a bipolar stimulation, or a multipolar stimulation. FIGS.13A-13E refer to switching from one configuration to anotherconfiguration. Those of ordinary skill in the art will understand, uponreading and comprehending this disclosure, that the neural stimulationtest routine is capable of switching among many electrodeconfigurations, including the switched electrode configurationsillustrated in FIGS. 13A-13E. Various embodiments use current steeringto change the direction of current flow. For example, in situationswhere current flows from both a first and second electrode to a thirdelectrode, the stimulation parameters can be adjusted, such as bychanging the applied potential between electrodes, to change thestimulation intensity and location between the first and thirdelectrodes and between the second and third electrodes.

Testing Electrode Configurations and Neural Stimulation

FIG. 14 illustrates a method for using the portable neural stimulator,according to various embodiments. An emergency responder, for example,can position the neural stimulation electrodes within the patient, asillustrated at 1461. The electrodes can be passed through the nose ormouth of the patient into the patients pharynx. The electrodes can befurther passed into the esophagus, larynx or trachea of the patient. At1462, the emergency responder actuates the device to initiate the neuralstimulation test routine to determine an electrode configuration thatcan be used to deliver effective neural stimulation. At 1463, the neuralstimulation is delivered based on the results of the neural testroutine. In various embodiments, the neural stimulation is automaticallydelivered using an electrode configuration determined by the testroutine to be able to be used to deliver effective neural stimulation.In various embodiments, the test routine provides results to theemergency responder, who can use the results to select an electrodeconfiguration determined by the test routine to be able to be used todeliver effective neural stimulation.

FIG. 15 illustrates a method for automatically performing a neuralstimulation test routine, according to various embodiments. In theillustrated embodiment, the electrode configuration is automaticallytested, as illustrated at 1564, to identify an electrode configurationthat is a candidate for use in delivering the neural stimulationtherapy. For example, a candidate electrode configuration can be aconfiguration where neural stimulation provides a discernable effect,although not as efficacious as desired. Once a candidate electrodeconfiguration is identified, the process proceeds to 1565, where theneural stimulation intensity is automatically tested to identify acandidate neural stimulation intensity for the candidate electrodeconfiguration. Various embodiments continue the test, collecting datacorresponding to different candidate electrode configurations anddifferent candidate neural stimulation intensities to assess whether acandidate is more or less effective than other candidates. Variousembodiments deliver the neural stimulation therapy using the firsteffective electrode configuration candidate and neural stimulationcandidate.

FIG. 16 illustrates a method for automatically performing the neuralstimulation test routine, according to various embodiments. At 1666, anelectrode configuration and neural stimulation intensity is selected. At1667, it is determined whether there is a desired response to neuralstimulation using the selected electrode configuration and neuralstimulation intensity. If there is a desired response, the processproceeds to 1668 to automatically deliver neural stimulation using theelectrode configuration and a candidate neural stimulation intensitythat provides the desired response. If a desired response is notdetected and if a time out flag is not received at 1669, the processproceeds to 1670 to adjust the electrode configuration from the currentelectrode configuration to an another electrode configuration (e.g.different electrodes, electrode combinations, vectors). If the electrodeconfiguration adjustments do not provide a desired response after apredetermined time or available electrode configurations have beenexhausted, the process for selecting an electrode configuration timesout at 1669, and the neural stimulation intensity is adjusted at 1671.After the neural stimulation intensity is adjusted, the process againdetermines whether there is a desired response to neural stimulation at1667 and adjusts the electrode configuration until there is a desiredresponse to the neural stimulation or until the process times out at1669. If the process times out, the neural stimulation intensity can beadjusted again at 1671. According to various embodiments, theillustrated method is an automatic process that is initiated by anactuator on the portable neural stimulator.

According to various embodiments, the device, as illustrated anddescribed above, is adapted to deliver neural stimulation as electricalstimulation to desired neural targets, such as through one or morestimulation electrodes positioned at predetermined location(s). Otherelements for delivering neural stimulation can be used. For example,some embodiments use transducers to deliver neural stimulation usingother types of energy, such as ultrasound, light, magnetic or thermalenergy.

One of ordinary skill in the art will understand that, the modules andother circuitry shown and described herein can be implemented usingsoftware, hardware, and combinations of software and hardware. As such,the terms module and circuitry are intended to encompass softwareimplementations, hardware implementations, and software and hardwareimplementations.

The methods illustrated in this disclosure are not intended to beexclusive of other methods within the scope of the present subjectmatter. Those of ordinary skill in the art will understand, upon readingand comprehending this disclosure, other methods within the scope of thepresent subject matter. The above-identified embodiments, and portionsof the illustrated embodiments, are not necessarily mutually exclusive.These embodiments, or portions thereof, can be combined. In variousembodiments, the methods are implemented using a computer data signalembodied in a carrier wave or propagated signal, that represents asequence of instructions which, when executed by a processor cause theprocessor to perform the respective method. In various embodiments, themethods are implemented as a set of instructions contained on acomputer-accessible medium capable of directing a processor to performthe respective method. In various embodiments, the medium is a magneticmedium, an electronic medium, or an optical medium.

It is to be understood that the above detailed description is intendedto be illustrative, and not restrictive. Other embodiments will beapparent to those of skill in the art upon reading and understanding theabove description. The scope of the invention should, therefore, bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

What is claimed is:
 1. A system for testing neural stimulation sites ina patient, the system comprising: a flexible tether adapted to be fedinto a throat of the patient to position stimulation electrodes withinthe throat of the patient in at least one of a pharynx, a larynx, atrachea, or an esophagus of the patient, wherein the pharynx, thelarynx, the trachea, and the esophagus are anatomical parts of thethroat, and the stimulation electrodes within the throat provideavailable electrode subsets for use to stimulate the neural stimulationsites such that each of the available electrode subsets includes atleast one stimulation electrode from the stimulation electrodes withinthe throat; a neural stimulation circuit adapted to deliver neuralstimulation; a sensor configured to sense a parasympathetic response;and a controller configured to implement a neural stimulation testroutine to: deliver neural stimulation through each of the availableelectrode subsets to stimulate, using at least one stimulation electrodefrom the stimulation electrodes within the throat, each of the neuralstimulation sites during the test routine; sense the parasympatheticresponse, using the sensor, when each of the neural stimulation sites isstimulated during the test routine; and identify one of the neuralstimulation sites as having a largest parasympathetic response to theneural stimulation delivered using at least one stimulation electrodefrom the stimulation electrodes within the throat, including using thesensed parasympathetic response when each of the neural stimulationsites is stimulated during the test routine.
 2. The system of claim 1,wherein the available electrode subsets include an electrode subset witha single electrode, the device further comprising at least one counterelectrode that is not included with the flexible tether for use inproviding at least one stimulation vector between the counter electrodeand the single electrode.
 3. The system of claim 1, wherein thecontroller is configured to control the neural stimulation circuit toselect a stimulation vector from at least two stimulation vectorsavailable for delivering neural stimulation, and the neural stimulationtest routine is configured to assess neural stimulation efficacy for theat least two stimulation vectors.
 4. The system of claim 1, wherein theflexible tether includes at least one lumen adapted to deliver a gas foruse by the patient in breathing.
 5. The system of claim 1, wherein theplurality of electrodes includes a first electrode positioned at a firstangular position about a circumference of the flexible tether, and asecond electrode positioned about a second angular position about thecircumference of the flexible tether.
 6. The system of claim 1, whereinthe system is configured to use at least some of the plurality ofelectrodes fed into the throat of the patient using the flexible tetherto detect heart rate.
 7. The system of claim 1, wherein the system isconfigured to use at least some of the plurality of electrodes fed intothe throat of the patient using the flexible tether to detect anelectrocardiogram (ECG) signal.
 8. The system of claim 1, wherein theflexible tether includes at least two distinct electrode regions, eachelectrode region including a plurality of electrodes.
 9. The system ofclaim 1, further comprising a carotid artery sensor configured to sensea cardiovascular parameter, wherein the carotid artery sensor includesan acoustic sensor configured to sense carotid artery blood flow anddetermine the cardiovascular parameter from the carotid artery bloodflow, the controller connected to the acoustic sensor to monitor theneural stimulation efficacy.
 10. The system of claim 1, wherein theneural stimulation sites include parasympathetic sites within a neck ofthe patient.
 11. The system of claim 1, further comprising a carotidartery sensor configured to sense a cardiovascular parameter, whereinthe carotid artery sensor includes a blood pressure sensor, thecontroller connected to the blood pressure sensor to monitor the neuralstimulation efficacy.
 12. The system of claim 1, further comprising acarotid artery sensor configured to sense a cardiovascular parameter,wherein the carotid artery sensor includes a heart rate sensor, thecontroller connected to the heart rate sensor to monitor the neuralstimulation efficacy.
 13. A method for testing neural stimulation siteswithin a patient, comprising: feeding a flexible tether into a throat ofthe patient to position stimulation electrodes within the throat of thepatient in at least one of a pharynx, a larynx, a trachea, or anesophagus of the patient, wherein the pharynx, the larynx, the trachea,and the esophagus are anatomical parts of the throat, and thestimulation electrodes within the throat provide available electrodesubsets for use to stimulate the neural stimulation sites in the patientsites such that each of the available electrode subsets includes atleast one stimulation electrode from the stimulation electrodes withinthe throat; implementing a programmed neural stimulation test routine todeliver neural stimulation through each of the available electrodesubsets to stimulate each of the neural stimulation sites during thetest routine, wherein implementing the programmed neural stimulationtest routine includes: delivering neural stimulation through each of theavailable electrode subsets to stimulate, using at least one stimulationelectrode from the stimulation electrodes within the throat, each of theneural stimulation sites during the test routine; sensing aparasympathetic response when each of the neural stimulation sites isstimulated during the test routine; and identifying one of the neuralstimulation sites as having a largest parasympathetic response to theneural stimulation delivered using at least one stimulation electrodefrom the stimulation electrodes within the throat, including using thesensed parasympathetic response when each of the neural stimulationsites is stimulated during the test routine.
 14. The method of claim 13,further comprising delivering a gas through a lumen in the flexibletether.
 15. The method of claim 13, wherein the neural stimulation sitesinclude parasympathetic sites.
 16. The method of claim 13, whereindelivering neural stimulation through each of the available electrodesubsets includes stimulating each of the neural stimulation sites usinga counter electrode on the patient and at least one of the stimulationelectrodes positioned in the patient.
 17. The method of claim 13,further comprising using an acoustic sensor to sense carotid arteryblood flow, and using the sensed carotid artery blood flow to determineblood pressure to assess the neural stimulation efficacy for each of thestimulated neural stimulation sites.
 18. The method of claim 13, furthercomprising using an acoustic sensor to sense carotid artery blood flow,and using the sensed carotid artery blood flow to determine heart rateto assess the neural stimulation efficacy for each of the stimulatedneural stimulation sites.
 19. The method of claim 13, wherein the neuralstimulation sites include parasympathetic sites within a neck of thepatient.